The more you pay the more info you will get. What cars do you want to scan? Manufactures must release codes relating to emissions, but alot of those generic scan tools will read a code out as a manufacture specific code then you must google to try and find the description. Some of the cheap tools will pull false or wrong codes, so that is no help either. What are you looking to do once you have the code, just clear them or fix the code yourself? I just see people come into work all the time that went to auto zone had codes pulled and put every part known to man on the car. Then the light is still on and they bring it to us, and we find a broken vacuum hose or something stupid like that and it fixes all there problems. Have a great day, Eric

I'm not trying to do anything particular -- just add some information to my arsenal. Many mechanics seem to be honest and well-intentioned but not all that competent at trouble shooting. For example, last summer a garage wanted to replace my Civic throttle body (for $700) due to codes caused indirectly by a bad ignition switch feeding bad voltage to the computer. Now if they were smart enough to recognize that the switch was bad, why weren't they smart enough to reset the codes and see if they came back after the switch was replaced? With a scan tool I could more easily have checked this stuff myself.

So you are saying each vehicle needs different software within the scan tool? I thought the whole idea of ODB2 was that the interface and the codes were standard across all cars. Not so??? Is it only the plug interface that is standard? I have shop manuals for both cars (thank you, eBay), so if the $25 unit would give me the code numbers, that should be enough.

I have a $20 OBD II scanner. It does exactly what I want..... it turns the dang light off so I can get an inspection sticker! It will give me the codes when scanned. I just go online and find out what it is. Even thought the old Van throws a code every 9 or 12 months, I have never thrown a code that made me do a repair. I have spoken to mechanics about it and they say "it was probably a loose gas cap". I figure if it runs fine and my gas mileage doesn't change, why should I start throwing parts at it? The two times I needed repairs it did not throw a code..... a bad intake gasket which I discovered when I found milky oil, and a bad blinker switch when I lost my brake lights. Two serious things and it never told me!

A generic OBD scanner will give you generic OBD "P" codes. Then manufacturers have specific codes for their models that you need specific scan tools for.

You have to remember, the OEM's want you to use their service departments so they aren't going to give you anything more than they have to.

I had a '96 Audi that wouldn't even accept the generic scanner. It physically wouldn't plug in.

Try looking at the Scantron website and see what meets your needs. I used their stuff when I worked at Parts America and it was decent stuff for a decent price. I don't think you want to be dropping a ton of dough on a Snap On type unit.

And after all this, you still have to be smarter than the scanner. It will tell you what code came up, but most of the time, that's not the problem. The internet is your friend here.

I have a Ford Windstar that would throw three codes. Turns out the intake manifold is sucking oil due to a design flaw. It's a know problem but not a recall because it doesn't affect safety. If it wasn't for the internet, i'd have spent the rest of my life throwing parts at it and still have to take it to a dealer where they wanted $2000 to fix something that cost me $200 and an evening of time.

Depending on your electronics skills it's possible to build an ODB to laptop computer interface. Then you can use the computer as a recorder to log a failure and the events that caused it. This usually beyond the skills of typical auto owner. But if you have an in depth interest search the electronic hobbyist sites like Circuit Cellar. See: http://www.circuitcellar.com/index.htmlThis link is broken, either the page no longer exists or there is some other issue like a typo. for general info

Circuit Cellar is a magazine I get. It sponsors, in conjunction with electronics parts manufacturers, an annual design contest. In 2006 the winner was a ODBII reader. See: http://www.circuitcellar.com/avr2006/winners/DE/AT2810.htmThis link is broken, either the page no longer exists or there is some other issue like a typo.

All the details are there, including schematics and parts list.

It uses a AVR brand of microcontroller to read the codes. If you want to really learn about automotive computers building an ODBII reader would be a good place to start.

Rberq, Get the cheapest one to clear and display codes. If you don't have other test equipment, seeing parameters and data values isn't going to help much, ecspecially if you don't know how to read them ( I am unsure of your skill level, maybe you have a great amount of knowledge, then get a better tool). The reason I say get the cheapest is if you spend a fair amount of money and it doesn't work you will be disapointed. I looked at the other scan tools, some seem pretty decent, but the one says full data coverage for $89, no way. That company did not get all the info from the manufacture to only charge $89. We have 12 scan tools at work 1 is a multipurpose one that cost 12grand and it still doesn't display all the parameters for all the cars. Alot of people have stuff that works for what they have, but your newer cars are more and more proprietary. Just the stuff I deal with at work every day. have a great day, Eric

I've got the www.Digimoto.com usb version for the laptop and also have a Actron Pocket Scan Code from Advance auto for 50% off. If you want just the codes, get the cheapest one and look the codes up on the web, you'll see hundreds of people with the same problem code as you, and their solutions.

Thanks for all the replies. It sounds like the simplest code displayer is the one for me.

I wonder how many shops have the really powerful tools, and how many mechanics really know how to use them. Do the proprietary and high-cost systems simply plug into the same under-dash connector, or are there additional connection points at the computer and/or at various sensors?

All the sensors are typically tested individually. When I worked at the parts store, the manufacturer(Wells), gave classes on how to test the major components. Usually, you only need a multimeter and a little know how. Again, the internet is your friend here.

As far as I know, the proprietary scanners plug into the same data port as the generic one.

Rberq, Yes there is one connector on all cars built model year 1996 and later, it is called the obdII diagnostic connector. All cars after 96 must have this, and they must all communicate on the same protocol for emissions related failures. Most new cars are going to what they call CAN(controller area network) same connector but differant communication protocol(So depending on the car you would need a can compatible scanner). That is where the similarities end, some cars still have a factory connector somewhere on the car, that is where you get the good info for climate control problems, body control problems, electronic suspensions ect, but than you need a scan tool that can read that and the appropiate connector. So to answer a question some cars have two connectors. Most cars ford, chrysler, GM, to name a few release all the info through the obdII connector, but you need there software to read it. If a scan tool Co. doesn't pay for the info other than emissions failures it will not be in there software. We have factory scan tools for Detroits big three, and numerous others. You almost have to, if you want to do any programming. Even then when you have the equipment, to do updates to a cars computer you still have to log onto a manufactures website(for a fee) to do the update, info gets downloaded into the scan tool and then to the cars computer. As for doing additional testing, when you test with a voltmeter you normally will not find problems unless it is real bad, typically you need a lab scope and you would test the sensor under it's operating conditions. On a side note The shop I work at specializes in electrical testing and difficult problems(weather it is mechanical or electrical) on cars. We get alot of referances from other shops, and every now and then a new car dealer will send us one of theirs. Always makes you feel good when you fix one the dealer couldn't Hope some of this info was useful, Eric

You can thank the global warming nutbags for even needing one of these in the first place. They WANT you to spend money you don't have on problems that aren't really problems!! I just went through this whole deal with the '00 Jimmy that I bought for my wife. Biggest turd ever built by any manufacturer.

I have a $700 scanner, but you still have to do a bit of troubleshooting to find the exact problem.

The easiest thing for me to do was to swear off any vehicle built after 1996. PROBLEM SOLVED!!!! I don't need to impress anyone with shiny paint, and neither does my wife. As long as the damn thing gets her to work. I couldn't care less if the purple unicorns are gagging on the exhaust fumes! Kiss my ass OBD II!!